The most recent phase began in 2001 and has primarily revolved around U.S. The war in Afghanistan has been on and off since 1978. Countries currently at war (as of September 2021): Category: 10,000+ casualties in 2020/2021 Afghanistan This article will use the Uppsala Conflict Data Program definition, which described war as 'a state-based conflict or dyad which reaches at least 1000 battle-related deaths in a specific calendar year.' Fatality figures include any combatants killed in action as well as any civilians who were deliberately killed (for example, by bombings or other attacks).

Conversely, not every ongoing armed conflict is classified as a war. Not all wars are formalized with official declarations of war between combatants.